Regulation via glutamate decarboxylase activity
The in vitro activity of purified, recombinant Petunia GAD has an
acidic pH optimum of ~5.5, with little activity at pH 7.0 in the
absence of calmodulin22. GAD is a cytosolic enzyme23, and it has
been suggested that stress-induced GABA synthesis is the result
of cytosolic acidosis and the consequent stimulation of GAD
(Ref. 24). This proposal is supported by in vivo experiments